If you get your boron and copper at an ag fertilizer dealer, it will have a
granule size that is similar to that of the regular NPK fertilizers.
You can also dissolve the fertilizer in water and spray it using a broadcast
spray rig. Sodium tetraborate and copper sulfate are both readily soluble
in water.
Be careful with the boron. If you are top dressing it (on a lawn for
example), rather than incorporating it, you can get phytotoxic
concentrations in the top inch or so of soil if you get a light rainfall
after application followed by dry weather. By the time the rains come to
move it deeper in the soil, your grass might be dead :-(